This invention concerns a keyless access system for a truck including, amongst others, a cargo area. This invention also concerns a truck equipped with such a system, a control unit to be used in such a system and a method to be implemented with such a system.
Keyless systems have been known to allow an easy access to a personal vehicle because the user does not have to open a door with a key in so far as a customer identification device or CID, which is often in the form of a remote controller or an electronic card or tag, is recognized by the system when the user comes close to a door or a vehicle.
An active electronic keyless access system is a system where a user actuates his remote controller, e.g. by pressing a button, to unlock a door of the vehicle. A passive keyless access system is a system where the user has a customer identification device which can exchange information with an onboard control unit without being manually actuated by the user. This invention applies to an active keyless access system and to a passive keyless access system.
As disclosed in U.S. Pat. No. 5,532,521, keyless systems have been used to control access to a cargo zone of a truck, which facilitates the work of the driver. When the driver wants to access the cargo zone, he must actuate a transmitter to generate a signal processed to open a rear access door. When exiting the storage area, the driver must tap a switch to close and lock the door. With this system, the driver must remember to open the rear door of the truck before leaving his seat and must not forget to close the door when re-entering the cabin. This is tedious, especially for vehicles which are used to deliver goods in several locations, like stores, in a city.
On the other hand, keyless access systems have been designed in order to control access and, in some instances as in FR-A-2 815 149, control an auxiliary equipment like an audio device. Such systems are not adapted for trucks. No known systems take into account the fact that the driver of a truck might wish to exit the cabin and to go to a rear door in order to access a cargo area, without having to remember to actuate a transmitter before leaving the cabin or a switch before leaving the cargo area.
The invention aims at providing a keyless access system which facilitates the work of a driver by providing an easy, automatic and secure access to the cargo area of a truck.
To this purpose, the invention concerns a keyless access system for a truck including a tractor area and a cargo area provided with at least an access door, this system comprising:                a main control unit located in the tractor area and adapted to interact with a customer identification device to selectively operate access means which allow or prevent access to a driver cabin of the vehicle,        a secondary control unit located in or near the cargo area and adapted to interact with the same customer identification device and to selectively operate an actuator which locks or unlocks the access door, and        bi-directional telecommunication means between the main unit and the secondary unit.        
Thanks to the invention, the secondary unit can be used to lock or unlock the access door to the cargo area depending on the fact that a person standing near this door and outside the truck has or not a customer identification device, hereafter called “CID”, known by the system as valid to access the cargo area.
According to further aspects of the invention, this system might incorporate one or several of the following features:                The communication means between the main and secondary units are wireless.        The secondary unit is adapted to interact with a CID in order to collect data from this device and to send some information representative of these data to the main unit which is adapted to determine, on the basis of the information received from the secondary unit, if the access door is to be opened for this CID and, if such is the case, to send to the secondary unit, a clearance signal for this door.        Each main or secondary unit is connected to at least an activation switch, at least a lock actuator, at least an antenna adapted to send an activation signal towards a CID and/or to receive a response signal from the CID. Preferably, each unit is connected to a low frequency antenna adapted to emit the activation signal towards a CID and to a high frequency antenna adapted to receive a response signal from the CID.        The secondary control unit comprises means to collect data from a CID, means to send to the main access unit a signal representative of the data collected from the CID1 means to receive from the main control unit a clearance signal and means to selectively operate, upon reception by the receiving means of a clearance signal from the main unit, an actuator which unlocks an access door to a cargo area of the vehicle.        Independent power supply means are provided, in or near the cargo area, for the secondary access unit.        The system is a passive keyless access system.        
The invention also concerns a truck including a tractor area and a cargo area provided with at least an access door, this vehicle being provided with a keyless access control system as explained here-above.
According to a first embodiment, such a truck includes a tractor and a trailer, said main unit being mounted on the tractor whereas the secondary unit is mounted on the trailer. According to another embodiment, the truck comprises a cargo structure fixed on a frame belonging to a tractor, the main unit being mounted on the tractor, whereas the secondary unit is mounted on the structure.
The invention also concerns a control unit which can be used as a secondary unit in a system as mentioned here-above. This unit comprises means to collect data from a CID, means to send to a remotely located other control unit a signal representative of the data collected from the CID, means to receive from this other unit a clearance signal and means to selectively operate, upon reception by the receiving means of a clearance signal from the other unit, an actuator which unlocks an access door to a cargo area of a truck.
Finally, the invention concerns a method which can be implemented with the system mentioned here-above in order to control access to a cargo area of a truck. This method comprises at least the following steps of:
a)—detecting an unlock request of an access door to a cargo area of the vehicle,
b)—sending, from a first control unit located in or near the cargo area, a challenge signal towards a CID,
c)—receiving a signal corresponding to a response of the device,
d)—verifying, in a main control unit located in a tractor area of the vehicle, if the received signal corresponds to a valid identification code,
e)—if the received signal corresponds to a valid identification code, sending from the main unit to the first unit, a clearance signal,
f)—when a clearance signal is received in the first unit from the main unit, sending an actuation signal to an actuator which mechanically unlocks the access door.
According to a first approach, before step c), the response signal of the CID is received by the first unit and then a signal representative of this response signal is sent by the first unit to the main control unit. Alternatively, during step c), the response signal of the CID is received directly by the main control unit.
Advantageously, the signal transmission between the first and main units is wireless. According to an advantageous aspect of the invention, the challenge signal is a low frequency signal whereas the response signal is a high frequency signal and communication between the first and main units takes place in high frequency mode.